ES2537384T3 - Horticultural LED lighting assembly - Google Patents

Abstract

A horticultural lighting apparatus comprising at least one Light Emitting Diode (LED) that has a) first spectral characteristics that include a peak in the wavelength range of 600 to 700 nm and arranged to show a half maximum maximum achura of at least 50 nm or more; b) second spectral characteristics with a maximum of 50 nm of full maximum half-maximum and arranged to show a peak wavelength in the range of 440 to 500 nm, and c) all or part of the emission at a wavelength of 600- 800 nm is generated using a conversion increasing the total or partial wavelength of the radiation power of the LED chip with at least one conversion material increasing the wavelength in proximity to the LED, and d) the emission at 500 wavelengths -600 nm is arranged to be reduced below the intensity in the band 400-500 nm and below the intensity in the band 600-700 nm.

Description

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DESCRIPTION

Horticultural LED lighting assembly

Background of the invention

Field of the Invention

The present invention relates to the use of LEDs in horticultural lighting applications. In particular, the present invention relates to a lighting apparatus for facilitating the growth of plants comprising at least one Light Emitting Diode (LED) having spectral characteristics that include a peak in the wavelength range of 600 to 700 nm The present invention also relates to novel light emission components that are particularly suitable for facilitating plant growth and which comprise a semiconductor chip composed of light emission.

Description of the related technique

On Earth the sun is the main source of visible (ie, light) and invisible electromagnetic radiation and the main factor responsible for the existence of life. The average daily net solar energy that the Earth reaches is approximately 28  10 ^ 23 J (that is, 265 EBtu). This value is 5500 times higher than the world's annual main energy consumption, estimated in 2007, which is 5 10 ^ 20 J. The spectral distribution of the sun's radiation, as can be measured on the Earth's surface, has a broad wavelength band between approximately 300 nm and 1000 nm.

However, only 50% of the radiation that reaches the surface is photosynthetically active radiation (PAR). The PAR, in accordance with the recommendations of the CIE (International Lighting Commission), comprises the wavelength region between 400 nm and 700 nm of the electromagnetic spectrum. The laws of photochemistry can generally express the way in which plants collect radiation. The dual character of radiation makes it behave as an electromagnetic wave when it propagates in space and as particles (i.e., photon or quantum of radiant energy) when it interacts with matter. Photoreceptors are the active elements that exist mainly in the leaves of the plant responsible for capturing photons and converting their energy into chemical energy.

Due to the photochemical nature of photosynthesis, the photosynthetic rate, which represents the amount of O2 evolution or the amount of CO2 fixation per unit of time, correlates well with the number of photons that fall per unit area per second. on a leaf surface. Therefore, the recommended amounts for the PAR are based on the quantum system and are expressed using the number of moles (mol) or micromoles (mol) of photons. The recommended term for reporting and quantifying instantaneous PAR measurements is photosynthetic photon flux density (PPFD), and is typically expressed in moles / m2 / s. This provides the number of moles of photons that fall on a surface per unit area per unit time. The term photosynthetic photon flow (PPF) is also frequently used to refer to the same amount.

Photoreceptors that exist in living organisms, such as plants, use the radiant energy captured to mediate important biological procedures. This mediation or interaction can take place in a variety of ways. Photosynthesis, together with photojournalism, phototropism and photomorphogenesis, are the four representative procedures related to the interaction between radiation and plants. The following expression shows the simplified chemical equation of photosynthesis:

6 H2O + 6 CO2 (+ photon energy) → C6H12O6 + 6 O2

As will be seen from the equation, carbohydrates, such as sugar glucose (C6H12O6), and oxygen (O2), are the main products of the photosynthesis process. These are synthesized from carbon dioxide (CO2) and water (H2O) using the energy of the photons harnessed using specialized photoreceptors, such as chlorophylls and converting it into chemical energy.

Through photosynthesis, radiant energy is also used as the main source of chemical energy, which is important for plant growth and development. Naturally, the equilibrium of the input-output reagents of the equation is also dependent on the quantity (i.e. number of photons) and the quality (i.e. photon energy) of the radiant energy and, consequently, also of the biomass produced from the plants. "Photojournalism" refers to the ability of plants to detect and measure the periodicity of radiation, phototropism to the movement of plant growth to and away from radiation, and photomorphogenesis to change in form in response to the quality and quantity of radiation.

Typical absorption spectra of the most common photosynthetic and photomorphogenetic photoreceptors, such as chlorophyll a, chlorophyll b and beta carotene, and the two interconvertible forms of phytochromes (Pfr and Pr) are presented in Figure 1.

Photomorphogenetic responses, unlike photosynthesis, can be achieved with amounts of light

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extremely low The different types of photosynthetic and photomorphogenetic photoreceptors can be grouped into at least three known photosystems: photosynthetic, phytochrome and cryptochrome or blue / UV-A (ultraviolet-A).

In the photosynthetic photosystem, the existing pigments are chlorophylls and carotenoids. Chlorophylls are located in the thylakoids of the chloroplasts located in the foliar mesophilic cells of plants. The amount or energy of radiation is the most significant aspect, since the activity of these pigments is closely related to the collection of light. The two most important absorption peaks of chlorophyll are located in the red and blue regions of 625 to 675 nm and 425 to 475 nm, respectively. Additionally, there are also other peaks located in the near UV (300-400 nm) and in the far red region (700-800 nm). Carotenoids such as xanthophylls and carotenes are located in the plastid organelles of chromoplasts in plant cells and absorb primarily in the blue region.

The phytochrome photosystem includes the two interconvertible forms of phytochromes, Pr and Pfr, which have their sensitivity peaks in the red at 660 nm and in the far red at 730 nm, respectively. Photomorphogenetic responses mediated by phytochromes are normally related to the detection of light quality through the ratio of red (R) to far red (FR) (R / FR). The importance of phytochromes can be assessed through the different physiological responses where they are involved, such as foliar expansion, perception of the neighbors, shadow avoidance, stem lengthening, seed germination and flowering induction. Although the shadow avoidance response is normally controlled by phytochromes through the detection of the R / FR ratio, blue light and the PAR level are also involved in the related adaptive morphological responses.

The photoreceptors sensitive to blue and UV-A (ultraviolet A) are found in the cryptochrome photosystem. Blue light absorption pigments include both cryptochromes and phototropins. They are involved in several different tasks, such as monitoring the quality, quantity, direction and periodicity of the light. The different groups of photoreceptors sensitive to blue and UV-A mediate important morphological responses such as endogenous rhythm, organ orientation, stem lengthening and stomatal opening, germination, foliar expansion, root growth and phototropism. Phototropins regulate the pigmentary content and the situation of photosynthetic organs and organelles to optimize light collection and photoinhibition. As with exposure to continuous far red radiation, blue light also promotes flowering through the mediation of cryptochromic photoreceptors. In addition, blue light sensitive photoreceptors (for example, flavins and carotenoids) are also sensitive to near ultraviolet radiation, where a sensitivity peak located at approximately 370 nm can be found. Cryptochromes are not only common to all plant species. Cryptochromes mediate a variety of light responses, including the incorporation of circadian rhythms into flowering plants such as Arabidopsis. Although radiation of wavelengths below 300 nm can be highly detrimental to the chemical bonds of molecules and to the structure of DNA, plants absorb radiation in this region as well. The radiation quality in the PAR region may be important to reduce the destructive effects of UV radiation. These photoreceptors are the most investigated and therefore their role in the control of photosynthesis and growth is reasonably well known. However, there is evidence of the existence of other photoreceptors, the activity of which may have an important role in mediating important physiological responses in the plant. Additionally, the interaction and nature of interdependence between certain groups of receptors are not well understood.

Photosynthesis is perhaps one of the oldest, best known and most important biochemical procedures in the world. The use of artificial light to replace or compensate for the low availability of daylight is a common practice, especially in northern countries during the winter season, for vegetable production and ornamental crops.

The moment of artificial electrical lighting began with the development by Thomas Edison in 1879 of the Edison bulb, commonly known today as the incandescent lamp. Due to its thermal characteristic, incandescence is characterized by a large amount of far red emission, which can reach approximately 60% of the total PAR. Despite the developments that have taken place for more than a century, the electrical efficiency of incandescent lamps, given by the efficiency of conversion between the electrical energy consumed (input) and emitted optical energy (output) in the visible spectral region, It is still very poor. It is typically about 10%. Incandescent light sources also suffer from low yields of life, typically the life time is not more than 1000 hours. In plant growth applications its use is limited.

The growth of ornamental plants is one of the applications where incandescent lamps can still be used. Floral initiation can be achieved with species that respond to long hours using overnight exposure at low photon creep rates using incandescent lamps. The high amount of far-red radiation emitted is used to control photomorphogenetic responses throughout the mediation of phytochromes.

Fluorescent lamps are more commonly used in plant growth applications than incandescent lamps. The conversion of electro-optical energy is more effective compared to incandescent lamps. Tubular type fluorescent lamps can achieve electrical efficiency values from

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typically about 20% to 30%, where more than 90% of the emitted photons are within the PAR region with typical life times of approximately 10,000 hours. However, specially designed long-life fluorescent lamps can reach lifespan of between 30,000 hours. In addition to its reasonable energy efficiency and lifetime, another advantage of fluorescent lamps in plant growth is the amount of blue radiation emitted. This can reach more than 10% of the total photon emission within the PAR, depending on the correlated color temperature (CCT) of the lamp. For this reason, fluorescent lamps are frequently used for total replacement of natural daylight radiation in rooms and closed growth chambers. The emitted light radiation is indispensable to achieve a balanced morphology of most crop plants through the mediation of the family of cryptochrome photoreceptors.

Metal halide lamps belong to the group of high intensity discharge lamps. The emission of visible radiation is based on the luminescent effect. The inclusion of metal halides during manufacturing allows the optimization of the spectral quality of the emitted radiation to some extent. Metal halide lamps can be used in plant growth to completely replace daylight or to partially complement it during the period of least availability. The high PAR output per lamp, the relatively high percentage of blue radiation of approximately 20% and the electrical efficiency of approximately 25%, makes metal halide lamps an option for crops throughout the year. Their operating times are typically 5,000 to 6,000 hours. The high pressure sodium lamp (HPS) has been the preferred light source for crop production throughout the year in greenhouses. The main reasons have been high radiant emission, low price, long life, high PAR emission and high electrical efficiency. These factors have allowed the use of high pressure sodium lamps as complementary lighting sources that support the growth of vegetables in a profitable way during the winter in northern latitudes.

However, the spectral quality in HPS lamps is not optimal for promoting photosynthesis and photomorphogenesis, resulting in foliar and excessive stem lengthening. This is due to the imbalanced spectral emission in relation to the absorption peaks of important photosynthetic pigments such as chlorophyll a, chlorophyll b and beta carotene. The low R / FR ratio and the low blue light emission compared to other sources induce excessive stem elongation in most crops grown under HPS lighting. The electrical efficiencies of high pressure sodium lamps are typically between 30% and 40%, which makes them the most effective energy sources used today in plant growth. Approximately 40% of the input energy is converted into photons within the PAR region and almost 25% to 30% in the far red and infrared. The operating times of high pressure sodium lamps are in the range of approximately 10,000 to 24,000 hours.

The low availability of daylight in northern latitudes and consumer demand for quality horticultural products at affordable prices throughout the year set demands for new lighting and biological technologies. Production yields can also be significantly increased globally if daylight is available up to 20 to 24 hours per day. Therefore, approaches that can reduce production costs, increase yields and crop quality are necessary. Lighting is simply one of the aspects involved that can be optimized. However, its importance cannot be underestimated. The increase in electricity prices and the need to reduce CO2 emissions are additional reasons for making efficient use of energy. In the production of crops throughout the year in greenhouses, the contribution of the cost of electricity for general costs can reach approximately 30% in some crops.

Although existing light sources commonly used for plant growth can have electrical efficiencies close to 40%, the overall system efficiency (i.e., including losses in excitators, reflectors and optics) can be significantly lower. The spectral quality of the radiation plays an important role in the healthy growth of the crop. Conventional light sources cannot be spectrally controlled during use without the inefficient and limited use of additional filters. In addition, the control of the amount of radiation is also limited, reducing the possibility of versatile lighting regimes such as pulsed operation.

Therefore, and for reasons related to the aspects described above, the light emitting diode and solid-state lighting (SSL) have emerged as potentially viable and promising tools for use in horticultural lighting. The internal quantum efficiency of LEDs is a measure for the percentage of photons generated by each electron injected into the active region. In fact, the best HB-LED AlInGaP in red and AlInGaN in green and blue can have internal quantum efficiencies better than 50%; Challenges remain to extract all the light generated outside the semiconductor device and the light element.

In horticultural lighting the main practical advantages of LED-based light sources in relation to conventional light sources are the directionality and full control capability of the emitted radiation. LEDs do not necessarily require reflectors, since they are naturally semi-isotropic emitters. LEDs as directional emitters prevent most of the losses associated with optics. Additionally, the narrow spectral bandwidth characteristic of color LEDs is another important advantage in relation to broad-wave light sources. The main advantage of using LEDs as sources of photosynthetic radiation results from the possibility of selecting the peak wavelength emission that most closely matches the peak of

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absorption of a selected photoreceptor. In fact, this possibility gives them additional advantages. The effective use of radiant energy by the photoreceptor in the mediation of a physiological response of the plant is one of the advantages. Another advantage is the ability to control the response by completely controlling the intensity of radiation.

The above mentioned advantages can be further extended to the level of the luminaire. The inventor knows a luminaire with a blue LED and a red LED. The spectral emission of AlInGaN LEDs with color is currently available from UV in the green region of the visible spectrum. Those devices can emit in the region of blue and UV-A where the absorption peaks of cryptochromes and carotenoids are located.

Chlorophyll a and the red isomeric form of phytochromes (Pr) have a strong absorption peak located at approximately 660 nm. AlGaAs LEDs emit in the same region but, partially due to low market demand and obsolete production technology, they are expensive devices when compared to phosphide-based or even nitride-based LEDs. AlGaAs LEDs can also be used to control the shape of the far red of phytochromes (Pfr), which have an important absorption peak at 730 nm.

AlInGaP LEDs are based on well-established material technology with relatively high optical and electrical performance. Typically, the spectral emission region characteristic of the AlInGaP red LEDs covers the region where chlorophyll b has its absorption peak, at approximately 640 nm. Therefore, AlInGaP LEDs are also useful in promoting photosynthesis.

The novel commercial high brightness LEDs are not suitable for greenhouse cultivation since their main emission peak lies in the range of green wavelengths that range from 500 to 600 nm and therefore do not respond to the procedure of photosynthesis. However, in principle according to the technique, an LED light to which photosynthesis responds can be constructed by combining various types of semiconductor LEDs such as AlInGaP and AlInGaN, for colors of red and blue.

There are a number of problems related to the combination of LED with color individually. Therefore, different types of semiconductor devices will age at different speeds and for this reason the color ratio of red to blue will vary over time, resulting in additional abnormalities in a plant growth procedure. A second major problem is that individual single color LEDs have relatively narrow spectral coverage, typically less than 25 nm, which is insufficient to provide good photosynthesis efficiency without using very high numbers of different color and individual LEDs and producing high cost. of the implementation.

It is known from EP 2056364 A1 and US 2009/0231832 that an improved number of colors can be generated from LEDs using wavelength conversion materials, such as phosphorus, to re-emit different colors of light. Supposedly, the different colors that replicate sunlight can be used to treat depression or seasonal illness according to US 2009/0231832. These documents are cited herein by reference.

These lights have many disadvantages, even if they were used as horticultural lights, for example due to the simple reason that the spectrum of sunlight is suboptimal for plant growth. The light of US 2009/0231832 which is intended to replicate sunlight contains many superfluous wavelengths that are not effectively used by growing plants. For example, the band of 500-600 nm (green light) is used poorly by plants since green plants reflect this wavelength. This leads to wasted energy in horticultural applications.

Additionally, prior art lights also omit essential wavelengths, which would be very useful for plant growth. For example, these lights do not reach far red between 700 nm-800 nm, which is important for plant cultivation.

Summary of the invention

It is an object of the present invention to eliminate at least part of the problems in relation to the technique and to provide a new way to facilitate plant growth using LEDs.

It is a first objective of the invention to provide a single source of light emission based on LED devices to which the photosynthesis procedure responds well.

It is a second objective of the invention to provide a lighting apparatus for greenhouse cultivation based on an optimized LED photon flow photon synthesis device (PPF).

It is a third objective of the invention to achieve an LED device that provides at least two emission peaks in the wavelength range of 300 to 800 nm and at least one of the emission peaks has Full Maximum Half Width (FWHM) of at minus 50 nm or more.

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It is a fourth objective of the invention to provide a LED-based greenhouse crop lighting apparatus in which the emission intensity ratio of two emission frequencies, 300-500 nm and 600-800 nm, is reduced by less than 20 % during 10,000 hours of operation.

It is a fifth objective of the invention to provide a technical solution that provides a better value of PPF per watt (i.e., PPF versus watts of power used) than that obtained by conventional high pressure sodium lamps used in greenhouse cultivation and which It therefore provides an effective light source of energy for the greenhouse cultivation process and artificial lighting used therein.

It is a sixth objective of the invention to provide a single source of light emission in which the emission at a wavelength of 300-500 nm is generated by the semiconductor LED chip and the emission at a wavelength of 600-800 nm It is generated using a conversion increasing the partial wavelength of the radiation power of the LED chip. The inventor has discovered that for example cucumber and lettuce plants reach greater length and / or mass when they are illuminated with the inventive horticultural light that includes far red light (700-800 nm).

It is a seventh objective of the invention to provide a single source of light emission where the wavelength emission of 300-500 nm is generated by the semiconductor LED chip and the wavelength emission of 600-800 nm is generated using a conversion by increasing the partial wavelength of the radiation power of the LED chip. Conversion by increasing the wavelength to produce 600-800 nm radiation is achieved using one or more conversion materials increasing the wavelength in proximity to the LED emission source.

In this application "conversion increasing wavelength" is interpreted as changing the wavelength of incoming absorbed light to emitted light of longer wavelengths.

It is an eighth objective of the invention to provide 400-500 nm, 600-800 nm or both partial wavelength or conversion intervals by increasing the full wavelength of semiconductor LED chip radiation, the chip having an emission range of 300-500 nm emission range. The conversion increasing the wavelength is done using organic, inorganic materials or combination of both types.

It is a ninth object of the invention to provide the conversion by increasing the wavelength using a nano-sized particle material for the conversion by increasing the wavelength.

It is a tenth objective of the invention to provide the conversion by increasing the wavelength using material similar to molecular for the conversion by increasing the wavelength.

It is an eleventh object of the invention to provide the conversion by increasing the wavelength using a polymeric material in which the conversion material increasing the wavelength is covalently bonded to the polymeric matrix that provides the conversion by increasing the wavelength.

It is a twelfth objective of the invention to present an LED-based lighting apparatus where the spectral band of 500-600 nm is suppressed. In this suppressed band there is hardly any or no broadcast at all,

or in any case less emission than in any of the adjacent 400-500 nm, 600-700 nm bands. The suppression can be achieved according to the invention by not having any or only a small amount of primary emission in the 400-500 nm band, and ensuring that any conversion increasing the wavelength produces a wavelength shift that displaces the length wave over 600 nm. It is generally known that green plants cannot use green light radiation (500-600 nm) as well as radiation in adjacent bands, since this radiation is simply reflected from the plant instead of being absorbed by photosynthetic conversion .

It is a thirteenth objective of the invention to present an LED-based lighting apparatus that maximizes the anabolic growth of plants by providing desired far red light, while minimizing the green light that from the perspective of plant cultivation is energy-wasting radiation. . This objective is achieved in one aspect of the invention by means of a blue LED with a conversion device increasing the wavelength that converts by increasing the wavelength part of the emitted blue light (300-500) nm into a red spectrum component wide (600-800 nm) that has a far red component, but omits and / or minimizes the green component (500-600 nm).

The present invention provides a light emitting diode and a related light element suitable for greenhouse cultivation. According to the invention, the light emitting diode has a specific emission frequency pattern, that is, it has at least two spectral characteristics; an emission peak with a full maximum half-maximum of at least 50 nm or more and having a peak wavelength in the range of 600 to 700 nm, and second spectral characteristics that have a peak wavelength below the range 500 nm The LED emission peaks coincide well with a response spectrum of plant photosynthesis and are therefore particularly suitable for high artificial lighting efficiency.

A light emission component suitable for facilitating plant growth, comprises a semiconductor chip composed of light emission; and a conversion match increasing the wavelength of light

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which is deposited in direct proximity of the LED chip. Such a component can emit two characteristic light emission peaks.

More specifically, the light apparatus according to the invention is characterized by the features of claim 1.

The best mode of the invention is considered to imply a plurality of LEDs in the wavelength range of 380-850 nm arranged with emission spectra that are arranged to match the photosynthetic response of a plant to be cultivated with the lighting of said LED. The best mode will characterize the conversion by increasing the wavelength by phosphorus from the blue LED emission.

Brief description of the drawings

Figure 1 shows relative absorption spectra of the most common photosynthetic and photomorphogenetic photoreceptors in green plants; Figure 2 shows the emission peaks of a first single-source LED light source device according to the invention; Figure 3 shows the emission peaks of a second single-source LED light source device according to the invention; Figure 4 shows the emission peaks of a third single-source LED light source device according to the invention; Figure 5 shows the emission peaks of a fourth single-source LED light source device according to the invention; and Figures 6a to 6c show in schematic manner the various process steps of a process for producing a modified LED device according to a preferred embodiment of the invention.

Detailed description of preferred embodiments

As discussed above, the present invention generally relates to a single-source LED light source device that has optimal properties to be used as a greenhouse crop light source. Specifically, this approach to building light sources has optimal properties and flexibility to match the frequencies of photosynthesis in plant culture. Using this approach, light sources can be designed to achieve superior PPF and PPF for efficiency and wattage performance and very low power consumption and very long operating life when compared to existing technologies.

In particular, the single light emission LED device provides at least two emission peaks in the wavelength range of 300-800 nm and at least one of the emission peaks has at least Full Width Semi-maximum (FWHM) 50 nm or higher. The emission peaks and relative intensities are selected to match the frequencies of photosynthesis for the plant. Also the amount of PPF required for the light source is optimized to meet the requirements of the plant.

The emission at a wavelength of 300-500 nm is generated by the semiconductor LED chip and the emission at the wavelength of 400-800 nm is generated using a conversion increasing the full or partial wavelength of the radiation power of the LED chip. The conversion by increasing the partial wavelength can be selected to be in the range of 5-95%, preferably 35-65%, of the radiation of the semiconductor LED chip. The conversion by increasing the wavelength to produce the radiation of 400-800 nm is achieved using one or more conversion materials increasing the wavelength in proximity to the LED emission source. The conversion increasing the wavelength is done using organic, inorganic materials or combination of both types. These materials can be particle materials (nano or other sized particles), molecular or polymeric. Additionally, the materials may have a structural arrangement that results in conversion by increasing the wavelength of the emission source.

According to a particular embodiment, a lighting apparatus to facilitate plant growth comprises a UV LED, optionally with external luminescent emission characteristics. LED typically shows

a) first phosphorescent spectral characteristics with a peak wavelength in the range of 350 to 550 nm; b) optional optional phosphorescent spectral characteristics with a peak wavelength in the range of 600 to 800 nm; and c) optional third phosphorescent spectral characteristics with a freely adjustable peak wavelength between 350 and 800 nm.

In this application peak wavelength "adjustable" as in the foregoing is interpreted as a peak wavelength that can be adjusted during assembly of the lighting fixture in the factory, and / or also "adjustable" as in an adjustable selector in the appliance of illumination to adjust peak wavelength at the site. Furthermore, adjusting the peak wavelengths of the LED during the LED manufacturing process is also in accordance with the

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invention, and "adjustable" should be construed to also include adjustments made during the LED manufacturing process. All the aforementioned embodiments of an adjustable peak wavelength, or any other adjustable light source or variable LED are within the scope of this patent application.

Preferably the phosphorescent emission intensities of the former, optionally of the latter and optionally of the third spectral characteristics are adjustable in any relationship.

Figures 2 to 5 illustrate a few examples of the emission peaks of single-source LED light source devices.

In Figure 2, the emission of the semiconductor LED chip reaches the peak at a wavelength of 457 nm with full-width Half-Maximum (FWHM) emission peaks of 25 nm. In this case the conversion increasing the wavelength is done using two conversion materials increasing the wavelength. These two conversion materials increasing the wavelength have individual emission peaks at 660 nm and 604 nm. Figure 2 shows the combined emission peak from these two conversion materials increasing the wavelength reaching the peak at 651 nm wavelength with 101 nm FWHM emission peaks. In this case approximately 40% (calculated from the peak intensities) of the emission of the semiconductor LED chip, is converted by increasing the wavelength to emission of 651 nm by two conversion materials increasing the individual wavelength.

In Figure 3, the emission of the semiconductor LED chip reaches the peak at a wavelength of 470 nm with full-width Half-Maximum (FWHM) emission peaks of 30 nm. In this case the conversion increasing the wavelength is done using two conversion materials increasing the wavelength. These two conversion materials increasing the wavelength have individual emission peaks at 660 nm and 604 nm. Figure 2 shows the combined emission peak from these two conversion materials increasing the wavelength reaching the peak at 660 nm wavelength with 105 nm FWHM emission peaks. In this case approximately 60% (calculated from the peak intensities) of the emission of the semiconductor LED chip, is converted by increasing the wavelength to emission of 660 nm by means of two individual "conversion increasing the wavelength" materials.

In Figure 4, the emission of the semiconductor LED chip reaches the peak at a wavelength of 452 nm with full-width Half-Maximum (FWHM) emission peaks of 25 nm (not shown in the figure). In this case the conversion increasing the wavelength is done using a conversion material increasing the wavelength.

Figure 3 shows the emission peak from this conversion material increasing the wavelength reaching peaks at a wavelength of 658 nm with emission peaks of 80 nm FWHM. In this case approximately 100% (calculated from the peak intensities) of the emission of the semiconductor LED chip, is converted by increasing the wavelength to emission of 658 nm by the conversion material increasing the wavelength. This can be indicated from Figure 4, as there is no 452 nm emission in the LED device.

In Figure 5, the emission of the semiconductor LED chip reaches the peak at a wavelength of 452 nm with full-width Half-Maximum (FWHM) emission peaks of 25 nm. In this case the conversion increasing the wavelength is done using a conversion material increasing the wavelength. Figure 5 shows the emission peak from this conversion material increasing the wavelength reaching the peak at 602 nm wavelength with 78 nm FWHM emission peaks. In this case approximately 95% (calculated from the peak intensities) of the emission of the semiconductor LED chip, is converted by increasing the wavelength to emission of 602 nm by the conversion material increasing the wavelength.

For the aforementioned spectrum the device can be constructed as explained in detail below. The emission frequency of the semiconductor LED chip should be selected in a manner that is appropriate to excite the phosphorus molecules used in the device. The emission from the LED chip can be between 400 nm and 470 nm.

The phosphorus molecule or molecules used should be selected in the manner that desired emission spectra are obtained from the LED.

In the following we will describe a procedure for using two phosphor materials (conversion materials increasing the wavelength) in the LED device to achieve the desired spectra (see Figures 6a to 6c).

Phosphorus A and phosphorus B are mixed in a pre-determined ratio to achieve the desired phosphorus emission spectra from the LED device (see Figure 6a). The match of matches can be for example

99: 1 (A: B) to 1:99. This mixture of A + B matches is mixed in a C material (for example a polymer) at a predetermined concentration to form an "encapsulant." The phosphorus concentration in material C can be for example 99: 1 (phosphorus mixture: material C) to 1:99. This mixture of material C + matches (A and B) is then deposited in direct proximity to the LED chip (Figure 6b and 6c). By "proximity" we want

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mean that it can be deposited directly on the surface of the LED chip or spaced with other optical material. The concentration of the phosphorus mixture in material C determines the amount of conversion by increasing the wavelength of the emission frequency of the semiconductor LED chip, which means how much of the emission frequency of the "original" LED chip is observed in the emission of the final LED device and how much phosphorus emission becomes in the LED device.

The thickness of the encapsulant (in which the phosphorus is mixed) typically ranges from 0.1 um to 20 mm, in particular from 1 um to 10 mm, preferably from 5 um to 10 mm, for example from about 10 um to 5 mm , depending on the phosphorus concentration.

Typically the phosphorus concentration (calculated from the total weight of the encapsulant) is about 0.1 to 20%, preferably about 1 to 10%.

The conversion increasing the wavelength can be 100%, which means that there is only phosphorus emission observed from the LED device or it can be less than 100%, which means that some of the LED chip emission is transmitted outside the LED device .

To summarize, by adjusting the phosphorus ratio A: B it is possible to adjust the desired phosphorus emission spectra from the LED device and by adjusting the phosphorus concentration in the material C it is possible to adjust the amount / emission value of the desired LED chip for the LED device

The amount (physical thickness) of material C (with a certain phosphorus concentration) in the upper part of the LED chip also affects the amount of emission of the LED chip that is transmitted from the LED device. The thicker the layer of material C on the top of the LED chip, the smaller the transmission.

The material C can be for example a solvent, inorganic or organic polymer, silicon polymer, siloxane polymer or another polymer where the phosphorus can be mixed. Material C may have one or more components that have to be mixed before using together with the phosphorus. Material C can be a thermally curable or UV curable material.

The mixture of phosphorus or phosphors and solvent material C (solid or liquid) can be translucent or transparent, preferably transparent, to allow the passage of light emitted from the LED.

In an embodiment that is especially preferred, far-red radiation (700-800 nm) is produced by for example phosphors co-doped with Europio-cerium Ba_x Sr_ and ZnS_3 and / or lanthanide oxide sulphides doped with cerium. These types of phosphors and sulphides have a maximum emission peak between 650-700 nm of the wavelength region and also show a half full maximum achura (50-200 nm) and therefore also produce light emission at wavelength higher, that is, above the 700 nm wavelength range.

In addition to or as an alternative to using matches or other similar materials it is also possible to perform the conversion by increasing the wavelength by means of at least one semiconductor quantum dot or the like, which is placed near the LED.

Example

An LED lighting apparatus was constructed for comparison testing purposes based on the single LED device that has identical output spectrum as in Figure 3. The lighting apparatus consisted of 60 individual LED units having a power consumption of 69 W which includes the power consumption of the AC / DC constant current controller.

The comparison devices were commercial HPS (High Pressure Sodium) lamp greenhouse lighting fixtures with total power consumption of 420 W and commercial LED greenhouse LED appliances. The commercial LED device was based on individual blue and red LED devices that have a total power consumption of 24 W.

The LED lighting apparatus according to the present invention was tested against the above-mentioned commercial LED devices using the following procedure and PPF measurement arrangement.

PAR irradiation (irradiation value between 400 nm and 700 nm) and PPF values were calculated by measuring the spectra of the light apparatus from 300 nm to 800 nm and the absolute irradiation value in the band from 385 nm to 715 nm . The spectrum of each lamp was measured with the ILT700A spectrometer at a distance. Absolute irradiation values were measured with precision pyranometer at certain distances and used later to calculate absolute spectra at these distances. These absolute spectra were used to calculate the PAR and PPF calculations. PAR irradiation (W / m2) was calculated by integrating the absolute spectrum from 400 nm to 700 nm. The PPF values were first calculated by translating the irradiation value of each “channel” of the W / m2 spectrum into microeinsteins and then integrating this spectrum through the desired wavelength band.

The result of the comparison of these two commercial greenhouse lamp elements and the LED apparatus according to the innovation are presented in the table below. The results were also normalized against the

E10774243

05-20-2015

commercial HPS lighting fixture.

LED of

HPS type LED of the invention

Growth of Ref.

Power (W) 420 24 69

Total PPF 164 26 88 PPF / Watt 0.39 1.08 1.28 Effectiveness of PPF standardized to HPS of Ref. 1.77 3.27 Effectiveness of PPF standardized to HPS of Ref. (%) 100% 277% 327 %

As will be seen from the test results shown, an LED lighting apparatus according to the present invention provides 3.27 times higher PPF efficiency compared to HPS and 1.18 times better efficiency of

5 PPF compared to the commercial LED greenhouse apparatus based on individual blue and red LED devices. Naturally, all LEDs or lighting devices are arranged especially for use in greenhouses for growing plants such as greenhouse lights in many embodiments of the invention.

The above examples have described embodiments in which there is a Light Emitting Diode (LED) that has the indicated spectral characteristics. Naturally, the present lighting apparatus may comprise a

10 plurality of LEDs, at least some (ie 10% or more) or preferably a majority (more than 50%) of which have the indicated properties and characteristics. It is therefore possible to have elements comprising combinations of conventional LEDs and LEDs of the present type. There are no particular upper limits to the number of LEDs. Therefore, lighting apparatus of the present type may have approximately 1 to 10,000 LEDs, typically 1 to 1000 LEDs, in particular 1 to 100 LEDs.

It is in accordance with the invention to include LEDs with different peak emissions in a luminaire and control these to provide a desirable spectral emission to achieve a certain growth result or physiological response. In this way, the lighting system would allow versatile control of the lighting intensity and spectrum. Finally, the control of other abiotic parameters such as CO2 concentration, temperature, daylight availability and humidity could be integrated into the same control system along with the lighting,

20 optimizing crop productivity and global greenhouse management.

References

EP 2056364 A1, Satou et al.

Document US 2009/0231832, Zukauskas et al.

Claims (3)

1. A horticultural lighting apparatus comprising at least one Light Emitting Diode (LED) that has a) first spectral characteristics that include a peak in the wavelength range of 600 to 700 nm and arranged to show a full maximum half-maximum of at least 50 nm or more; 5 b) second spectral characteristics with a maximum of 50 nm of full maximum half-maximum and arranged to show a peak wavelength in the range of 440 to 500 nm, and c) all or part of the emission at a wavelength of 600 -800 nm is generated using a conversion increasing the total or partial wavelength of the radiation power of the LED chip with at least one conversion material increasing the wavelength in proximity of the LED, and 10 d) the emission at wavelengths of 500-600 nm is arranged to be reduced below the intensity in the band of 400-500 nm and below the intensity in the band of 600-700 nm 2. The lighting apparatus of claim 1, wherein the LED has spectral characteristics with a freely adjustable peak in the wavelength range of 500 to 800 nm and arranged to show at least 30 nm of full maximum half-width .

The lighting apparatus of any one of claims 1, comprising a second LED with at least one spectral characteristic with a maximum of 50 nm of full maximum half-maximum and a peak wavelength in the range of 400 to 500 nm and optionally second and third spectral characteristics arranged to have freely adjustable peak wavelengths in the range of 450 nm to 800 nm.

4. Use of the lighting apparatus of claim 1 to provide light for at least one plant.

A method for improving plant growth in which at least one lighting apparatus of claim 1 emits light to at least one plant.

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